Indoor and outdoor units for an HVAC system

ABSTRACT

A heating, ventilating, and air conditioning (HVAC) system includes a compressor configured to circulate a fluid through the HVAC system, a first coil configured to establish a first heat exchange relationship between the fluid and a first airflow across the first coil, a second coil configured to establish a second heat exchange relationship between the fluid and a second airflow across the second coil, and a fan configured to direct the first airflow across the first coil, the second airflow across the second coil, or both, and where the first airflow across the first coil is directed to be isolated from the second airflow across the second coil, and the first airflow is blocked from flowing across the first coil when the first coil is inactive and the second airflow is blocked from flowing across the second coil when the second coil is inactive.

CROSS REFERENCE TO RELATED APPLICATION

This application benefits from the priority of U.S. Provisional PatentApplication No. 62/404,650, entitled “Method to Increase the IntegratedEnergy Efficiency Ratio,” filed Oct. 5, 2016, which is herebyincorporated by reference in its entirety.

BACKGROUND

The present disclosure relates generally to environmental controlsystems, and more particularly, to improved indoor and outdoor units forenvironmental control systems.

Environmental control systems are utilized in residential, commercial,and industrial environments to control environmental properties, such astemperature and humidity, for occupants of the respective environments.The environmental control system may control the environmentalproperties through control of an airflow delivered to the environment.For example, a heating, ventilating, and air conditioning (HVAC) systemincludes heat exchange units (e.g., indoor and outdoor units) that placethe airflow in a heat exchange relationship with a working fluid (e.g.,refrigerant) to heat and/or cool the airflow. Traditionally, heatexchange units of HVAC systems are rated based on an energy efficiencyratio (EER) that measures an efficiency of a respective heat exchangeunit when operating at full capacity. Recent regulations have introducedan integrated energy efficiency ratio (IEER) that rates a respectiveheat exchange unit based on weighted efficiencies of the respective heatexchange unit at partial loads. Unfortunately, existing heat exchangeunits that have relatively high ratings based on EER may have low IEERsbecause of reduced performance at partial loads.

SUMMARY

In one embodiment, a heating, ventilating, and air conditioning (HVAC)system includes a compressor configured to circulate a working fluidthrough the HVAC system, a first coil configured to receive the workingfluid and to establish a first heat exchange relationship between theworking fluid and a first airflow across the first coil, a second coilconfigured to receive the working fluid and to establish a second heatexchange relationship between the working fluid and a second airflowacross the second coil, and a fan configured to direct the first airflowacross the first coil, the second airflow across the second coil, orboth, and where the first airflow across the first coil is directed tobe isolated from the second airflow across the second coil, and thefirst airflow is blocked from flowing across the first coil when thefirst coil is inactive and the second airflow is blocked from flowingacross the second coil when the second coil is inactive.

In another embodiment, a heating, ventilating, and air conditioning(HVAC) system includes a compressor configured to circulate a workingfluid through the HVAC system, a first coil configured to receive theworking fluid and to establish a first heat exchange relationshipbetween the working fluid and a first airflow across the first coil, asecond coil configured to receive the working fluid and to establish asecond heat exchange relationship between the working fluid and a secondairflow across the second coil, a barrier positioned between the firstcoil and the second coil, where the barrier is configured to isolate thefirst airflow across the first coil from the second airflow across thesecond coil, a fan configured to direct the first airflow across thefirst coil, the second airflow across the second coil, or both, a sensorconfigured to determine an operating state of the first coil and thesecond coil, and a control system configured to receive feedback fromthe sensor indicative of an operating state of the first coil and thesecond coil, block the first airflow across the first coil when thefeedback indicates that first coil is inactive, block the second airflowacross the second coil when the feedback indicates that the second coilis inactive, direct the first airflow across the first coil when thefeedback indicates that the first coil is active, and direct the secondairflow across the second coil when the feedback indicates that thesecond coil is active.

In another embodiment, a method includes receiving feedback indicativeof an operating state of a coil of a heat exchange unit, determiningwhether a working fluid is flowing through the coil of the heat exchangeunit based on the feedback, blocking an airflow across the coil of theheat exchange unit when the feedback indicates that the working fluid isnot flowing through the coil of the heat exchange unit, and directing asecond airflow across the coil of the heat exchange unit when thefeedback indicates that the working fluid is flowing through the coil ofthe heat exchange unit.

DRAWINGS

FIG. 1 is a perspective view of an environmental control for buildingenvironmental management that may employ one or more HVAC units, inaccordance with an aspect of the present disclosure;

FIG. 2 is a perspective view of an embodiment of the environmentalcontrol system of FIG. 1, in accordance with an aspect of the presentdisclosure;

FIG. 3 is a perspective view of a residential heating and coolingsystem, in accordance with an aspect of the present disclosure;

FIG. 4 is a schematic of an embodiment of a vapor compression systemthat can be used in any of the systems of FIGS. 1-3, in accordance withan of aspect the present disclosure;

FIG. 5 is a schematic of an embodiment of an indoor unit that may beused in the systems of FIGS. 1-3, in accordance with an aspect of thepresent disclosure;

FIG. 6 is a perspective view of an embodiment of an indoor unit that maybe used in the systems of FIGS. 1-3, in accordance with an aspect of thepresent disclosure;

FIG. 7 is a schematic of an embodiment of an indoor unit that may beused in the systems of FIGS. 1-3, in accordance with an aspect of thepresent disclosure;

FIG. 8 is a schematic of an embodiment of an outdoor unit that may beused in the systems of FIGS. 1-3, in accordance with an aspect of thepresent disclosure;

FIG. 9 is a schematic of an embodiment of an outdoor unit that may beused in the systems of FIGS. 1-3, in accordance with an aspect of thepresent disclosure;

FIG. 10 is a schematic of an embodiment of an outdoor unit that may beused in the systems of FIGS. 1-3, in accordance with an aspect of thepresent disclosure;

FIG. 11 is a schematic of an embodiment of an outdoor unit that may beused in the systems of FIGS. 1-3, in accordance with an aspect of thepresent disclosure; and

FIG. 12 is a block diagram of an embodiment of a process for operatingthe indoor and outdoor units of FIGS. 5-10, in accordance with an aspectof the present disclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure are directed toward improved heatexchange units (e.g., indoor and outdoor heat exchange units) that areutilized in heating, ventilating, and air conditioning (HVAC) systems.More specifically, embodiments of the present disclosure are directed toheat exchange units of an HVAC system that have an increased integratedenergy efficiency ratio (IEER). Traditionally, heat exchange units ofHVAC systems are rated based on an energy efficiency ratio (EER). TheEER calculates a rating of a respective heat exchange unit based on anefficiency of the respective heat exchange unit when operating at fullcapacity (e.g., 100% load). For example, the EER may be determined basedon an output capacity of the heat exchange unit at full load and anamount of power input to the heat exchange unit to operate the heatexchange unit at full load conditions. Recent regulations rate heatexchange units of HVAC systems based on an integrated energy efficiencyratio (IEER), which calculates a rating based on weighted efficienciesof a respective heat exchange unit at partial loads. For example, theIEER may emphasize an efficiency of the respective heat exchange unitwhen operating at 75% load as opposed to the EER, which calculates arating based only on full load efficiency. In some cases, heat exchangeunits that operate with relatively high EERs may have low IEERs as aresult of reduced efficiency when operating at partial loads.

Accordingly, embodiments of the present disclosure are directed towardimproved heat exchange units that operate with an increased IEER whencompared to existing heat exchange units. It is now recognized that theIEER is reduced when airflow is directed over inactive coils of the heatexchange unit or coils that do not include a flow of working fluid. Forexample, when a heat exchange unit operates at a partial load, workingfluid of the heat exchange unit may bypass one or more coils of the heatexchange unit to reduce an amount of heating and/or cooling of theairflow. Existing heat exchange units direct the airflow over all of thecoils in the heat exchange unit regardless of operating mode. Toincrease the IEER, embodiments of the present disclosure include one ormore separators or partitions that isolate coils within the heatexchange unit from one another.

In some embodiments, the separators may be positioned between each coilof the heat exchange unit to isolate the coils from one another.Accordingly, the separators may form sections within the heat exchangeunit and each section may include a corresponding fan and/or compressor.In other embodiments, a fan and/or compressor may be shared betweensections of the heat exchange unit that are formed by the separators.Further, in some embodiments, the separators may be louvers that enablesequential flow between sections of the heat exchange unit when thelouvers are in an open position and block flow between sections of theheat exchange unit when the louvers are in a closed position.Accordingly, the louvers may be adjusted from the open position to theclosed position when a coil of the heat exchange unit is inactive and noworking fluid flows through the coil. In some embodiments, the fansincluded in the heat exchange unit are variable speed fans, such that aflow rate of the airflow through the heat exchange unit is reduced whenone or more coils are inactive. In other embodiments, the fans may beplenum fans that may be powered on when a corresponding coil is activeand powered off when the corresponding coil is inactive. In any case,heat exchange units of the present disclosure isolate inactive coilsfrom active coils to block airflow over the inactive coils when the unitoperates at partial loads. Blocking airflow over the inactive coilsincreases the IEER of the heat exchange unit.

Turning now to the drawings, FIG. 1 illustrates a heating, ventilating,and air conditioning (HVAC) system for building environmental managementthat may employ one or more HVAC units. In the illustrated embodiment, abuilding 10 is air conditioned by a system that includes an HVAC unit12. The building 10 may be a commercial structure or a residentialstructure. As shown, the HVAC unit 12 is disposed on the roof of thebuilding 10; however, the HVAC unit 12 may be located in other equipmentrooms or areas adjacent the building 10. The HVAC unit 12 may be asingle package unit containing other equipment, such as a blower,integrated air handler, and/or auxiliary heating unit. In otherembodiments, the HVAC unit 12 may be part of a split HVAC system, suchas the system shown in FIG. 3, which includes an outdoor HVAC unit 58and an indoor HVAC unit 56.

The HVAC unit 12 is an air cooled device that implements a refrigerationcycle to provide conditioned air to the building 10. Specifically, theHVAC unit 12 may include one or more heat exchangers across which an airflow is passed to condition the air flow before the air flow is suppliedto the building. In the illustrated embodiment, the HVAC unit 12 is arooftop unit (RTU) that conditions a supply air stream, such asenvironmental air and/or a return air flow from the building 10. Afterthe HVAC unit 12 conditions the air, the air is supplied to the building10 via ductwork 14 extending throughout the building 10 from the HVACunit 12. For example, the ductwork 14 may extend to various individualfloors or other sections of the building 10. In certain embodiments, theHVAC unit 12 may be a heat pump that provides both heating and coolingto the building with one refrigeration circuit configured to operate indifferent modes. In other embodiments, the HVAC unit 12 may include oneor more refrigeration circuits for cooling an air stream and a furnacefor heating the air stream.

A control device 16, one type of which may be a thermostat, may be usedto designate the temperature of the conditioned air. The control device16 also may be used to control the flow of air through the ductwork 14.For example, the control device 16 may be used to regulate operation ofone or more components of the HVAC unit 12 or other components, such asdampers and fans, within the building 10 that may control flow of airthrough and/or from the ductwork 14. In some embodiments, other devicesmay be included in the system, such as pressure and/or temperaturetransducers or switches that sense the temperatures and pressures of thesupply air, return air, and so forth. Moreover, the control device 16may include computer systems that are integrated with or separate fromother building control or monitoring systems, and even systems that areremote from the building 10.

FIG. 2 is a perspective view of an embodiment of the HVAC unit 12. Inthe illustrated embodiment, the HVAC unit 12 is a single package unitthat may include one or more independent refrigeration circuits andcomponents that are tested, charged, wired, piped, and ready forinstallation. The HVAC unit 12 may provide a variety of heating and/orcooling functions, such as cooling only, heating only, cooling withelectric heat, cooling with dehumidification, cooling with gas heat, orcooling with a heat pump. As described above, the HVAC unit 12 maydirectly cool and/or heat an air stream provided to the building 10 tocondition a space in the building 10.

As shown in the illustrated embodiment of FIG. 2, a cabinet 24 enclosesthe HVAC unit 12 and provides structural support and protection to theinternal components from environmental and other contaminants. In someembodiments, the cabinet 24 may be constructed of galvanized steel andinsulated with aluminum foil faced insulation. Rails 26 may be joined tothe bottom perimeter of the cabinet 24 and provide a foundation for theHVAC unit 12. In certain embodiments, the rails 26 may provide accessfor a forklift and/or overhead rigging to facilitate installation and/orremoval of the HVAC unit 12. In some embodiments, the rails 26 may fitinto “curbs” on the roof to enable the HVAC unit 12 to provide air tothe ductwork 14 from the bottom of the HVAC unit 12 while blockingelements such as rain from leaking into the building 10.

The HVAC unit 12 includes heat exchangers 28 and 30 in fluidcommunication with one or more refrigeration circuits. Tubes within theheat exchangers 28 and 30 may circulate refrigerant (for example,R-410A, steam, or water) through the heat exchangers 28 and 30. Thetubes may be of various types, such as multichannel tubes, conventionalcopper or aluminum tubing, and so forth. Together, the heat exchangers28 and 30 may implement a thermal cycle in which the refrigerantundergoes phase changes and/or temperature changes as it flows throughthe heat exchangers 28 and 30 to produce heated and/or cooled air. Forexample, the heat exchanger 28 may function as a condenser where heat isreleased from the refrigerant to ambient air, and the heat exchanger 30may function as an evaporator where the refrigerant absorbs heat to coolan air stream. In other embodiments, the HVAC unit 12 may operate in aheat pump mode where the roles of the heat exchangers 28 and 30 may bereversed. That is, the heat exchanger 28 may function as an evaporatorand the heat exchanger 30 may function as a condenser. In furtherembodiments, the HVAC unit 12 may include a furnace for heating the airstream that is supplied to the building 10. While the illustratedembodiment of FIG. 2 shows the HVAC unit 12 having two of the heatexchangers 28 and 30, in other embodiments, the HVAC unit 12 may includeone heat exchanger or more than two heat exchangers.

The heat exchanger 30 is located within a compartment 31 that separatesthe heat exchanger 30 from the heat exchanger 28. Fans 32 draw air fromthe environment through the heat exchanger 28. Air may be heated and/orcooled as the air flows through the heat exchanger 28 before beingreleased back to the environment surrounding the rooftop unit 12. Ablower assembly 34, powered by a motor 36, draws air through the heatexchanger 30 to heat or cool the air. The heated or cooled air may bedirected to the building 10 by the ductwork 14, which may be connectedto the HVAC unit 12. Before flowing through the heat exchanger 30, theconditioned air flows through one or more filters 38 that may removeparticulates and contaminants from the air. In certain embodiments, thefilters 38 may be disposed on the air intake side of the heat exchanger30 to prevent contaminants from contacting the heat exchanger 30.

The HVAC unit 12 also may include other equipment for implementing thethermal cycle. Compressors 42 increase the pressure and temperature ofthe refrigerant before the refrigerant enters the heat exchanger 28. Thecompressors 42 may be any suitable type of compressors, such as scrollcompressors, rotary compressors, screw compressors, or reciprocatingcompressors. In some embodiments, the compressors 42 may include a pairof hermetic direct drive compressors arranged in a dual stageconfiguration 44. However, in other embodiments, any number of thecompressors 42 may be provided to achieve various stages of heatingand/or cooling. As may be appreciated, additional equipment and devicesmay be included in the HVAC unit 12, such as a solid-core filter drier,a drain pan, a disconnect switch, an economizer, pressure switches,phase monitors, and humidity sensors, among other things.

The HVAC unit 12 may receive power through a terminal block 46. Forexample, a high voltage power source may be connected to the terminalblock 46 to power the equipment. The operation of the HVAC unit 12 maybe governed or regulated by a control board 48. The control board 48 mayinclude control circuitry connected to a thermostat, sensors, and alarms(one or more being referred to herein separately or collectively as thecontrol device 16). The control circuitry may be configured to controloperation of the equipment, provide alarms, and monitor safety switches.Wiring 49 may connect the control board 48 and the terminal block 46 tothe equipment of the HVAC unit 12.

FIG. 3 illustrates a residential heating and cooling system 50, also inaccordance with present techniques. The residential heating and coolingsystem 50 may provide heated and cooled air to a residential structure,as well as provide outside air for ventilation and provide improvedindoor air quality (IAQ) through devices such as ultraviolet lights andair filters. In the illustrated embodiment, the residential heating andcooling system 50 is a split HVAC system. In general, a residence 52conditioned by a split HVAC system may include refrigerant conduits 54that operatively couple the indoor unit 56 to the outdoor unit 58. Theindoor unit 56 may be positioned in a utility room, an attic, abasement, and so forth. The outdoor unit 58 is typically situatedadjacent to a side of residence 52 and is covered by a shroud to protectthe system components and to prevent leaves and other debris orcontaminants from entering the unit. The refrigerant conduits 54transfer refrigerant between the indoor unit 56 and the outdoor unit 58,typically transferring primarily liquid refrigerant in one direction andprimarily vaporized refrigerant in an opposite direction.

When the system shown in FIG. 3 is operating as an air conditioner, aheat exchanger 60 in the outdoor unit 58 serves as a condenser forre-condensing vaporized refrigerant flowing from the indoor unit 56 tothe outdoor unit 58 via one of the refrigerant conduits 54. In theseapplications, a heat exchanger 62 of the indoor unit functions as anevaporator. Specifically, the heat exchanger 62 receives liquidrefrigerant (which may be expanded by an expansion device, not shown)and evaporates the refrigerant before returning it to the outdoor unit58.

The outdoor unit 58 draws environmental air through the heat exchanger60 using a fan 64 and expels the air above the outdoor unit 58. Whenoperating as an air conditioner, the air is heated by the heat exchanger60 within the outdoor unit 58 and exits the unit at a temperature higherthan it entered. The indoor unit 56 includes a blower or fan 66 thatdirects air through or across the indoor heat exchanger 62, where theair is cooled when the system is operating in air conditioning mode.Thereafter, the air is passed through ductwork 68 that directs the airto the residence 52. The overall system operates to maintain a desiredtemperature as set by a system controller. When the temperature sensedinside the residence 52 is higher than the set point on the thermostat(plus a small amount), the residential heating and cooling system 50 maybecome operative to refrigerate additional air for circulation throughthe residence 52. When the temperature reaches the set point (minus asmall amount), the residential heating and cooling system 50 may stopthe refrigeration cycle temporarily.

The residential heating and cooling system 50 may also operate as a heatpump. When operating as a heat pump, the roles of heat exchangers 60 and62 are reversed. That is, the heat exchanger 60 of the outdoor unit 58will serve as an evaporator to evaporate refrigerant and thereby coolair entering the outdoor unit 58 as the air passes over the outdoor heatexchanger 60. The indoor heat exchanger 62 will receive a stream of airblown over it and will heat the air by condensing the refrigerant.

In some embodiments, the indoor unit 56 may include a furnace system 70.For example, the indoor unit 56 may include the furnace system 70 whenthe residential heating and cooling system 50 is not configured tooperate as a heat pump. The furnace system 70 may include a burnerassembly and heat exchanger, among other components, inside the indoorunit 56. Fuel is provided to the burner assembly of the furnace 70 whereit is mixed with air and combusted to form combustion products. Thecombustion products may pass through tubes or piping in a heat exchanger(that is, separate from heat exchanger 62), such that air directed bythe blower 66 passes over the tubes or pipes and extracts heat from thecombustion products. The heated air may then be routed from the furnacesystem 70 to the ductwork 68 for heating the residence 52.

FIG. 4 is an embodiment of a vapor compression system 72 that can beused in any of the systems described above. The vapor compression system72 may circulate a refrigerant through a circuit starting with acompressor 74. The circuit may also include a condenser 76, an expansionvalve(s) or device(s) 78, and an evaporator 80. The vapor compressionsystem 72 may further include a control panel 82 that has an analog todigital (A/D) converter 84, a microprocessor 86, a non-volatile memory88, and/or an interface board 90. The control panel 82 and itscomponents may function to regulate operation of the vapor compressionsystem 72 based on feedback from an operator, from sensors of the vaporcompression system 72 that detect operating conditions, and so forth.

In some embodiments, the vapor compression system 72 may use one or moreof a variable speed drive (VSDs) 92, a motor 94, the compressor 74, thecondenser 76, the expansion valve or device 78, and/or the evaporator80. The motor 94 may drive the compressor 74 and may be powered by thevariable speed drive (VSD) 92. The VSD 92 receives alternating current(AC) power having a particular fixed line voltage and fixed linefrequency from an AC power source, and provides power having a variablevoltage and frequency to the motor 94. In other embodiments, the motor94 may be powered directly from an AC or direct current (DC) powersource. The motor 94 may include any type of electric motor that can bepowered by a VSD or directly from an AC or DC power source, such as aswitched reluctance motor, an induction motor, an electronicallycommutated permanent magnet motor, or another suitable motor.

The compressor 74 compresses a refrigerant vapor and delivers the vaporto the condenser 76 through a discharge passage. In some embodiments,the compressor 74 may be a centrifugal compressor, a scroll compressor,a reciprocating compressor, a screw compressor, a tandem compressor, oranother suitable compressor. The refrigerant vapor delivered by thecompressor 74 to the condenser 76 may transfer heat to a fluid passingacross the condenser 76, such as ambient or environmental air 96. Therefrigerant vapor may condense to a refrigerant liquid in the condenser76 as a result of thermal heat transfer with the environmental air 96.The liquid refrigerant from the condenser 76 may flow through theexpansion device 78 to the evaporator 80.

The liquid refrigerant delivered to the evaporator 80 may absorb heatfrom another air stream, such as a supply air stream 98 provided to thebuilding 10 or the residence 52. For example, the supply air stream 98may include ambient or environmental air, return air from a building, ora combination of the two. The liquid refrigerant in the evaporator 80may undergo a phase change from the liquid refrigerant to a refrigerantvapor. In this manner, the evaporator 38 may reduce the temperature ofthe supply air stream 98 via thermal heat transfer with the refrigerant.Thereafter, the vapor refrigerant exits the evaporator 80 and returns tothe compressor 74 by a suction line to complete the cycle.

In some embodiments, the vapor compression system 72 may further includea reheat coil in addition to the evaporator 80. For example, the reheatcoil may be positioned downstream of the evaporator relative to thesupply air stream 98 and may reheat the supply air stream 98 when thesupply air stream 98 is overcooled to remove humidity from the supplyair stream 98 before the supply air stream 98 is directed to thebuilding 10 or the residence 52.

It should be appreciated that any of the features described herein maybe incorporated with the HVAC unit 12, the residential heating andcooling system 50, or other HVAC systems. Additionally, while thefeatures disclosed herein are described in the context of embodimentsthat directly heat and cool a supply air stream provided to a buildingor other load, embodiments of the present disclosure may be applicableto other HVAC systems as well. For example, the features describedherein may be applied to mechanical cooling systems, free coolingsystems, chiller systems, or other heat pump or refrigerationapplications.

As set forth above, present embodiments are directed to the HVAC unit12, which could be an indoor unit or an outdoor unit, having an improvedintegrated energy efficiency ratio (IEER). The IEER of the HVAC unit 12decreases when an airflow through the HVAC unit 12 is directed over aninactive coil of the HVAC unit 12. Accordingly, embodiments of thepresent disclosure are directed to isolating inactive coils of the HVACunit 12 from active coils, such that the airflow through the HVAC unit12 does not flow over the inactive coils. For example, FIG. 5 is aschematic of an embodiment of the HVAC unit 12, such as an indoor unit,that includes a first evaporator 100 and a second evaporator 102disposed in the cabinet 24. While the illustrated embodiment of FIG. 5shows the HVAC unit 12 having two evaporators, other embodiments of theHVAC unit 12 may include more than two evaporators. In any case, theHVAC unit 12 also includes a fan 104, such as a variable speed fan, thatdirects an airflow 106 through the HVAC unit 12. For example, the fan104 draws air into the cabinet 24 from an environment surrounding thecabinet 24, over the first evaporator 100 and/or the second evaporator102, and out of the cabinet 24 (e.g., to the ductwork 14).

As shown in the illustrated embodiment of FIG. 5, a louver 108 ispositioned between the first evaporator 100 and the second evaporator102. Additionally, the louver 108 may be further positioned upstreamand/or downstream of the second evaporator 102 with respect to theairflow 106 through the cabinet 24. As used herein, the louver 108 is adivider having adjustable slats that may be opened and closed (e.g.,manually or with the control board 48 and/or the control panel 82) basedon operation of the first evaporator 100 and the second evaporator 102.For example, the louver 108 may be in an open position when both thefirst evaporator 100 and the second evaporator 102 are in an activestate, such as when a working fluid flows through the first evaporator100 and the second evaporator 102. Accordingly, the airflow 106 isdirected over coils of both the first evaporator 100 and the secondevaporator 102 to establish a heat exchange relationship between theairflow 106 and the working fluid in both the first evaporator 100 andthe second evaporator 102.

In some embodiments, the second evaporator 102 is inactive when the HVACunit 12 operates at a partial load, such as when a heating or coolingdemand is reduced. In other words, the working fluid may bypass thesecond evaporator 102 and/or otherwise not flow through the secondevaporator 102 when the HVAC unit 12 operates at partial loadconditions. As such, the louver 108 may be switched from the openposition to the closed position to block the airflow 106 from flowingover the second evaporator 102. Switching the louver 108 from the openposition to the closed position may include adjusting a position of theslats of the louver 108, such that the louver 108 forms a solid wallbetween the first evaporator 100 and the second evaporator 102. When inthe closed position, the louver 108 separates the cabinet 24 of the HVACunit 12 into a first section 110 and a second section 112, where theairflow 106 flows through the first section 110 but not the secondsection 112. Therefore, airflow 106 is blocked from flowing over theinactive second evaporator 102, which increases the IEER of the HVACunit 12.

In some embodiments, a control system 113, such as the control board 48and/or the control panel 82 adjusts the louver 108 from the openposition to the closed position, and vice versa. The control system 113may adjust the louver 108 between the open and closed positions based onfeedback received from one or more sensors. For example, the HVAC unit12 may include sensor 114, such as a load sensor, a flow sensor, apressure sensor, a voltage sensor coupled to a compressor, and/oranother suitable sensor that provides feedback to the control system 113indicative of a status of the second evaporator 102. The control system113 may adjust the louver 108 from the open position to the closedposition when the feedback indicates that the second evaporator 102 hasswitched from active to inactive. Similarly, the control system 113 mayadjust the louver 108 from the closed position to the open position whenthe feedback indicates that the second evaporator 102 has switched frominactive to active. In other embodiments, the louver 108 is adjustedmanually. In such embodiments, the HVAC unit 12 may include an indicator116 that alerts an operator when the second evaporator 102 switchesbetween the active and inactive conditions. In still furtherembodiments, the control system 113 monitors operation of a compressorsupplying working fluid to the second evaporator 102 and adjusts thelouver 108 based on operation of the compressor. For example, when avoltage supplied to the compressor and/ the compressor speed falls belowa threshold, the control system 113 may close the louver 108 to blockthe airflow 106 over the second evaporator 102. In such embodiments, thecontrol system 113 may include a switch that automatically adjusts thelouver 108 to the closed position when an operating parameter of thecompressor supplying the working fluid to the second evaporator 102falls below a threshold, indicating that the compressor is notoperating. In any case, the louver 108 blocks the airflow 106 fromflowing over coils of the second evaporator 102 when the secondevaporator 102 is inactive, thereby increasing the IEER of the HVAC unit12.

In the illustrated embodiment of FIG. 5, the first evaporator 100 andthe second evaporator 102 are positioned side by side relative to theairflow 106 through the cabinet 24. However, in other embodiments, thefirst evaporator 100 is positioned below the second evaporator 102 (asshown in dashed lines in FIG. 5). For example, FIG. 6 is a perspectiveview of an embodiment of the HVAC unit 12 having the evaporators 100 and102 positioned in a stacked arrangement. As shown in the illustratedembodiment of FIG. 6, a barrier 118 is positioned between the firstevaporator 100 and the second evaporator 102 with respect to a height119 of the cabinet 24. Thus, the cabinet 24 is separated into the firstsection 110 and the second section 112 by the barrier 118. Further, thelouver 108 is positioned on an intake side 120 of the cabinet 24 andaligned with the second evaporator 102 along the height 119 of thecabinet 24. The fan 104 is positioned adjacent to an outlet side 122 ofthe cabinet 24 or in another suitable position in the cabinet 24 that isdownstream of the evaporators 100 and 102 with respect to the airflow106. As such, the fan 104 draws the airflow 106 across both the firstevaporator 100 and the second evaporator 102 when the louver 108 is inthe open position. When the louver 108 is adjusted to the closedposition, the airflow 106 is blocked from flowing across the secondevaporator 102 because air is blocked from being drawn into the secondsection 112 of the cabinet 24 by the louver 108. While the louver 108 isillustrated in alignment with the second evaporator 102, in otherembodiments, the louver 108 may be aligned with the first evaporator 100along the height 24 of the cabinet. In any case, the louver 108 blocksairflow across the first evaporator 100 and/or the second evaporator 102when the first evaporator 100 and/or the second evaporator 102 are in aninactive state, respectively.

FIG. 7 is a schematic of an embodiment of the HVAC unit 12, such as anindoor unit, that includes a first fan 130 corresponding to the firstevaporator 100 and a second fan 132 corresponding to the secondevaporator 102. In some embodiments, the first fan 130 and the secondfan 132 may be plenum fans. As used herein, a plenum fan is a fan thatdoes not include a separate housing from the HVAC unit 12 and dischargesair in multiple directions (e.g., into the ductwork 14). Plenum fans mayinclude a single speed and may operate at relatively low capacities,such that a single plenum fan provides a sufficient airflow 134 and/or136 over a respective evaporator 100 and/or 102 to achieve a desiredheating load or cooling load for the building 10. As shown in theillustrated embodiment of FIG. 7, the first evaporator 100 and thesecond evaporator 102, and thus the first fan 130 and the second fan132, are separated by a divider 138. The divider 138 may be a solidbarrier, such as a wall, that isolates the airflow 134 from the airflow136. In some embodiments, the louver 108 may be positioned downstream ofthe fan 132 with respect to the airflow 136 to block recirculation ofthe airflow 134 when the evaporator 102 is inactive. The airflow 136 andthe airflow 134 ultimately converge into the ductwork 14, for example,and thus, the airflow 134 may flow toward the evaporator 102 from theductwork 14. As such, the louver 108 may be closed when the evaporator102 is inactive to block the airflow 134 from flowing back toward theevaporator 102. In other embodiments, the fan 132 may include inletguide vanes that are configured to block the airflow 134 toward theevaporator 102 from the ductwork.

When the first evaporator 100 or the second evaporator 102 switches froman active state to an inactive state, the first fan 130 or the secondfan 132 is powered off. For example, when the first evaporator 100 is inthe inactive state, the first fan 130 is powered off to interrupt theairflow 134 through the HVAC unit 12. Similarly, when the secondevaporator 102 is in the inactive state, the second fan 132 is poweredoff to interrupt the airflow 136 through the HVAC unit 12. Therefore,when either the first evaporator 100 or the second evaporator 102switches to the inactive state, the airflow 134 or 136 is stopped, suchthat air does not flow over inactive coils of the HVAC unit 12. As aresult, the IEER of the HVAC unit is increased.

In some embodiments, the control system 113 is communicatively coupledto the first fan 130 and the second fan 132. Additionally, the controlsystem 113 receives feedback from the sensor 114 indicative of thestatus of the first evaporator 100 and/or the second evaporator 102.Accordingly, the control system 113 may selectively operate the firstfan 130 and the second fan 132 based on the feedback from the sensor114. For example, when the sensor 114 indicates that the firstevaporator 100 is in an inactive state, the control system 113 mayinterrupt a power supply to the first fan 130, such that the airflow 134does not flow over the coils of the first evaporator 100. Similarly,when the sensor 114 indicates that the second evaporator 102 is in aninactive state, the control system 113 may interrupt a power supply tothe second fan 132, such that the airflow 136 does not flow over thecoils of the second evaporator 102. As such, air does not flow over thefirst evaporator 100 or the second evaporator 102 when the firstevaporator 100 or the second evaporator 102 are in the inactive state,respectively, which increases the IEER of the HVAC unit 12.

In some embodiments, the HVAC unit 12, such as an outdoor unit, includescondensers that receive working fluid from a compressor and place theworking fluid in a heat exchange relationship with an airflow throughthe HVAC unit 12. For example, FIG. 8 is a schematic of an embodiment ofthe HVAC unit 12 having a first condenser 160, a second condenser 162, athird condenser 164, and a fourth condenser 166. Additionally, the HVACunit 12 includes a first fan 168, a second fan 170, a third fan 172, anda fourth fan 174. The condensers 160, 162, 164, and/or 166 as well asthe fans 168, 170, 172, and/or 174 may be equally sized and include thesame capacity. In other embodiments, the condensers 160, 162, 164,and/or 166 as well as the fans 168, 170, 172, and/or 174 may includedifferent sizes and capacities. For example, in some embodiments, thefans 168, 170, 172, and/or 174 may be multi-speed fans and/or variablespeed fans. Additionally or alternatively, the fans 168, 170, 172,and/or 174 may be operated utilizing a control scheme, such as a controlscheme that operates the fans 168, 170, 172, and/or 174 based on headpressure of the working fluid. As shown in the illustrated embodiment ofFIG. 8, the HVAC unit 12 of the illustrated embodiment of FIG. 8 is afour-stage unit that may operate using any combination of the condensers160, 162, 164, and/or 166. While the illustrated embodiment of FIG. 8shows the HVAC unit 12 having four condensers, in other embodiments theHVAC unit 12 may include less than four condensers or more than fourcondensers. The condensers 160, 162, 164, and 166 are isolated from oneanother by dividers 176. The dividers 176 form a first section 178having the first condenser 160 and the first fan 168, a second section180 having the second condenser 162 and the second fan 170, a thirdsection 182 having the third condenser 164 and the third fan 172, and afourth section 184 having the fourth condenser 166 and the fourth fan174.

In some embodiments, the dividers 176 form a cross shape to separate thecabinet 24 of the HVAC unit 12 into the sections 178, 180, 182, and/or184. In other embodiments, the dividers 176 form another suitable shape(e.g., see FIGS. 8-10) to separate the cabinet 24 into any suitablenumber of sections. The dividers 176 may be formed from the samematerial as the cabinet 24 and may be integral with the cabinet 24. Forexample, the dividers 176 may include a metallic material, such asstainless steel, steel, aluminum, copper, etc., that is the samematerial as the cabinet 24. In other embodiments, the dividers 176 mayinclude a polymeric material, such as plastic, that blocks airflowbetween sections within the cabinet 24. In still further embodiments,the dividers 176 may include any suitable material that blocks airflowbetween the sections 178, 180, 182, and 184 of the cabinet 24.

In the illustrated embodiment of FIG. 8, the HVAC unit 12 also includesa first compressor 186 in the first section 178, a second compressor 188in the second section 180, a third compressor 190 in the third section182, and a fourth compressor 192 in the fourth section 184. In otherembodiments, a compressor may be shared between condensers 160, 162,164, and/or 166 of the sections 178, 180, 182, and/or 184. Thecompressors 186, 188, 190, and/or 192 may be equally sized and includethe same capacity. In other embodiments, the compressors 186, 188, 190,and/or 192 may include different sizes and capacities. For example, thecompressors 186, 188, 190, and/or 192 may include multi-stagedcompressors, multi-speed compressors, tandem compressors, and/orvariable speed compressors. In any case, the compressors 186, 188, 190,and/or 192 control a flow rate of working fluid through the condensers160, 162, 164, and/or 166. As discussed above, the HVAC unit 12 includesfour stages, such that the HVAC unit 12 may operate with working fluidflowing through one, two, three, or all four of the condensers 160, 162,164, and/or 166. To increase the IEER of the HVAC unit 12, the fans 168,170, 172, and/or 174 and the compressors 186, 188, 190, and/or 192 maybe selectively operated based on an operating state (e.g., active stateor inactive state) of the condensers 160, 162, 164, and/or 166.

For example, the first fan 168 receives power and directs an airflow 194across coils of the first condenser 160 when working fluid flows throughthe coils of the first condenser 160, such as via the first compressor186. Additionally, the second fan 170 receives power and directs anairflow 196 across coils of the second condenser 162 when working fluidflows through the coils of the second condenser 162, such as via thesecond compressor 188. The third fan 172 receives power and directs anairflow 198 across coils of the third condenser 164 when working fluidflows through the coils of the third condenser 164, such as via thethird compressor 190. Further, the fourth fan 174 receives power anddirects an airflow 200 across coils of the fourth condenser 166 whenworking fluid flows through the coils of the fourth condenser 166, suchas via the fourth compressor 192.

In some embodiments, the HVAC unit 12 includes sensors 202 that providefeedback to the control system 113 indicative of an operating state ofthe condensers 160, 162, 164, and/or 166. Accordingly, the controlsystem 113 may selectively operate the fans 168, 170, 172, and 174 basedon the feedback received from the sensors 202. Airflow may not flow overthe coils of inactive condensers 160, 162, 164, and/or 166, which mayincrease the IEER of the HVAC unit 12.

FIG. 9 is a schematic of an embodiment of the HVAC unit 12, such as anoutdoor unit, that includes three condensers and three fans. Forexample, in the illustrated embodiment of FIG. 9, the HVAC unit 12includes a first condenser 220 and a corresponding first fan 222, asecond condenser 224 and a corresponding second fan 226, and a thirdcondenser 228 and a corresponding third fan 230. Condensers 220, 224,and 228 can each have capacities that are equal to one another, or inother embodiments, the condensers 220, 224, and 228 may have differentcapacities. In some embodiments, the fans 222, 226, and/or 230 may bemulti-speed fans and/or variable speed fans. Additionally oralternatively, the fans 222, 226, and/or 230 may be operated utilizing acontrol scheme, such as a control scheme that operates the fans 222,226, and/or 230 based on head pressure of the working fluid. Thecapacity of each of the condensers 220, 224, and/or 228 may be greaterthan the capacity of the condensers 160, 162, 164, and 166 of the HVACunit 12 of FIG. 8. The dividers 176 of the HVAC unit 12 of FIG. 9 form afirst section 232 having the first condenser 220 and the first fan 222,a second section 234 having the second condenser 224 and the second fan226, and a third section 236 having the third condenser 228 and thethird fan 230. The HVAC unit 12 may further include a first compressor238, a second compressor 240, and a third compressor 242 correspondingto the respective condensers 220, 224, and 228. In other embodiments, asingle compressor may be shared between two or more of the condensers220, 224, and 228. In some embodiments, the compressors 238, 240, and/or242 may include multi-staged compressors, multi-speed compressors,tandem compressors, and/or variable speed compressors. In any case,working fluid may circulate through one or more of the condensers 220,224, and 228 when the HVAC unit 12 operates to heat or cool the building10. Accordingly, the illustrated embodiment of the HVAC unit 12 of FIG.9 has at least three stages of heating and/or cooling.

For example, the first fan 222 receives power and directs an airflow 244across coils of the first condenser 220 when the working fluid flowsthrough the coils of the first condenser 220, for example, via the firstcompressor 238. Additionally, the second fan 226 receives power anddirects an airflow 246 across coils of the second condenser 224 when theworking fluid flows through the coils of the second condenser 244, forexample, via the second compressor 240. Further, the third fan 230receives power and directs an airflow 248 across coils of the thirdcondenser 228 when the working fluid flows through the coils of thethird condenser 228, for example, via the third compressor 242. Toincrease the IEER of the HVAC unit 12, the fans 222, 226, and 230 may beselectively operated based on an operating state of the condensers 220,224, and 228.

In some embodiments, the HVAC unit 12 includes sensors 250 that providefeedback to the control system 113 indicative of an operating state ofthe condensers 220, 224, and 228. Accordingly, the control system 113may selectively operate the fans 222, 226, and 230 based on the feedbackreceived from the sensors 250. Airflow may not flow over the coils ofinactive condensers 220, 224, and/or 228, which may increase the IEER ofthe HVAC unit 12.

FIG. 10 is a schematic of an embodiment of the HVAC unit 12 having twocondensers and four fans, where two fans may direct air across coils ofa single condenser. For example, the HVAC unit 12 includes a firstcondenser 270 and a second condenser 272 separated by the divider 176. Afirst fan 274 and a second fan 276 direct an airflow 278 across coils ofthe first condenser 270 and a third fan 280 and a fourth fan 282 directan airflow 284 across coils of the second condenser 272. In someembodiments, the fans 274, 276, 280, and/or 282 may be multi-speed fansand/or variable speed fans. Additionally or alternatively, the fans 274,276, 280, and/or 282 may be operated utilizing a control scheme, such asa control scheme that operates the fans 274, 276, 280, and/or 282 basedon head pressure of the working fluid. Additionally, the HVAC unitincludes a first compressor 286 and a second compressor 288 thatcirculate working fluid through the coils of the first condenser 270 andthe second condenser 272, respectively. The compressors 286 and 288 maybe multi-stage compressors, multi-speed compressors, tandem compressors,and/or variable speed compressors having the same or differentcapacities. In other embodiments, the HVAC unit 12 includes a singlecompressor. In any case, working fluid may circulate through one or bothof the condensers 270 and 272 when the HVAC unit 12 operates to heat orcool the building 10.

The HVAC unit 12 may operate with four stages of heating or coolingbased on the operating state of the condensers 270 and 272, as well asan operating state of the fans 274, 276, 280, and 282. For example, whenworking fluid is directed through the coils of the first condenser 270,the first fan 274 and/or the second fan 276 may flow the airflow 278across the first condenser 270. When only one of the first fan 274 andthe second fan 276 operates, the HVAC unit 12 may operate at a firststage of heating or cooling, such as approximately 25% capacity. Whenboth the first fan 274 and the second fan 276 operate, the HVAC unit 12may operate at a second stage of heating or cooling, such asapproximately 50% capacity. Further, when working fluid is also directedthrough the coils of the second condenser 272, the third fan 280 and/orthe fourth fan 282 may flow the airflow 284 across the coils of thesecond condenser 272. When only one of the third fan 280 and the fourthfan 282 operates, the HVAC unit 12 may operate at a third stage ofheating or cooling, such as when the working fluid is directed throughthe coils of the first condenser 270 and both the first fan 274 and thesecond fan 276 operate the HVAC unit 12. When operating at the thirdstage of heating or cooling, the HVAC unit 12 may operate atapproximately 75% capacity, for example. Additionally, when both thethird fan 280 and the fourth fan 282 operate, the HVAC unit 12 mayoperate at a fourth stage of heating or cooling, such as when theworking fluid is also directed through the coils of the first condenser270 and both the first fan 272 and the second fan 276 operate, the HVACunit 12 operates at approximately 100% capacity. In other embodiments,the fans 274, 276, 280, and 282 may be variable speed fans that mayenable the HVAC unit 12 to operate with more than four stages ofcooling.

In some embodiments, the HVAC unit 12 includes sensors 290 that providefeedback to the control system 113 indicative of an operating state ofthe condensers 270 and 272. Accordingly, the control system 113 mayselectively operate the fans 274, 276, 280, and 282 based on thefeedback received from the sensors 290. Airflow may not flow over thecoils of inactive condensers 270 or 272, which may increase the IEER ofthe HVAC unit 12.

FIG. 11 is a schematic of an embodiment of the HVAC unit 12 having twodifferent condenser sizes. For example, the HVAC unit includes a firstcondenser 310 and a second condenser 312. An airflow 314 is directedacross the first condenser 310 by a first fan 316, a second fan 318,and/or a third fan 320, whereas an airflow 322 is directed across thesecond condenser 312 by a fourth fan 324. Accordingly, the firstcondenser 310 may include a capacity that is approximately (e.g., within5% of, within 10% of, or within 20% of) three times greater than acapacity of the second condenser 312. In some embodiments, the fans 316,318, and/or 320 may be multi-speed fans and/or variable speed fans.Additionally or alternatively, the fans 316, 318, and/or 320 may beoperated utilizing a control scheme, such as a control scheme thatoperates the fans 316, 318, and/or 320 based on head pressure of theworking fluid. Further, the HVAC unit 12 includes a first compressor 326that circulates working fluid (e.g., refrigerant) through the firstcondenser 310 and a second compressor 328 that circulates working fluidthrough the second condenser 312. In some embodiments, the firstcompressor 326 has a capacity that is approximately (e.g., within 5% of,within 10% of, or within 20% of) three times greater than a capacity ofthe second compressor 328. In other embodiments, the HVAC unit 12 mayinclude a single compressor that circulates the working fluid throughboth the first condenser 310 and the second condenser 312. Additionallyor alternatively, the compressors 310 and 312 may include multi-stagedcompressors, multi-speed compressors, tandem compressors, and/orvariable speed compressors.

The HVAC unit 12 may operate with four stages of heating or coolingbased on the operating state of the condensers 310 and 312 as well as anoperating state of the fans 316, 318, 320, and 324. For example, whenworking fluid is directed through the coils of the first condenser 310,the first fan 316, the second fan 318, and/or the third fan 320 may flowthe airflow 314 across the first condenser 310. When only one of thefirst fan 316, the second fan 318, and the third fan 320 operates, theHVAC unit 12 may operate at a first stage of heating or cooling, such asapproximately 25% capacity. When two of the first fan 316, the secondfan 318, and the third fan 320 operate, the HVAC unit 12 may operate ata second stage of heating or cooling, such as approximately 50%capacity. Further, when all three of the first fan 316, the second fan318, and the third fan 320 operate, the HVAC unit 12 may operate at athird stage of heating or cooling, such as approximately 75% capacity.Additionally, when working fluid is also directed through the coils ofthe second condenser 312 and the fourth fan 324 flows the airflow 322across the coils of the second condenser 272, the HVAC unit 12 mayoperate at a fourth stage of heating or cooling, such as approximately100% capacity. In other embodiments, the fans 316, 318, 320, and/or 324may be variable speed fans that may enable the HVAC unit 12 to operatewith more than four stages of cooling.

In some embodiments, the HVAC unit 12 includes sensors 330 that providefeedback to the control system 113 indicative of an operating state ofthe condensers 310 and 312. Accordingly, the control system 113 mayselectively operate the fans 316, 318, 320, and/or 324 based on thefeedback received from the sensors 330. Airflow may not flow over thecoils of inactive condensers 310 and/or 312, which may increase the IEERof the HVAC unit 12.

FIG. 12 is a block diagram of an embodiment of a process 350 that may beutilized to control operation of embodiments of the HVAC unit 12 of thepresent disclosure. For example, at block 352 the control system 113receives feedback from the sensors 114, 202, 250, 290, and/or 330indicative of an operating state of a coil, such as an evaporator or acondenser coil, of the HVAC unit 12. Accordingly, at block 354, thecontrol system 113 determines whether a respective coil is active orinactive. In other words, the feedback from the sensors 114, 202, 250,290, and/or 330 indicates whether working fluid flows through therespective coil, and thus, whether the coil is active or inactive.

At block 356, the control system 113 blocks an airflow across therespective coil when the respective coil is inactive. As discussedabove, the control system 113 may actuate the louver 108 to a closedposition, such that the airflow does not flow across the respective coilwhen in the inactive state. In other embodiments, the control system 113may interrupt a power supply to a fan when the respective coil is in theinactive state, such that the airflow does not flow across therespective coil. In such embodiments, the respective coil and fan areisolated from an active coil and a fan that receives a power supply,such that the airflow to the active coil is blocked from flowing acrossthe respective coil.

At block 358, the control system 113 directs airflow across therespective coil when the respective coil is active. As discussed above,the control system 113 may actuate the louver 108 to an open position,such that the airflow flows across the respective coil when in theactive state. In other embodiments, the control system 113 may restore apower supply to a fan when the respective coil is in the active state,such that the airflow flows across the respective coil. Blocking airflowacross inactive coils and isolating active coils from inactive coilsincreases an IEER of the HVAC unit 12 by increasing an efficiency of theHVAC unit 12 at partial loads.

As set forth above, the heat exchange units of the present disclosuremay provide one or more technical effects useful in the operation ofHVAC systems. For example, embodiments of the present approach isolateactive coils of a heat exchange unit from inactive coils of the heatexchange unit to increase an integrated energy efficiency ratio (IEER)of the heat exchange unit. The IEER calculates a rating for a heatexchange unit based on efficiencies of the heat exchange unit at partialloads. Accordingly, blocking airflow across inactive coils of the heatexchange unit increases the IEER by enhancing an efficiency of the heatexchange unit at partial operating loads. The technical effects andtechnical problems in the specification are examples and are notlimiting. It should be noted that the embodiments described in thespecification may have other technical effects and can solve othertechnical problems.

While only certain features and embodiments have been illustrated anddescribed, many modifications and changes may occur to those skilled inthe art (e.g., variations in sizes, dimensions, structures, shapes andproportions of the various elements, values of parameters (e.g.,temperatures, pressures, etc.), mounting arrangements, use of materials,colors, orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter recited in the claims.The order or sequence of any process or method steps may be varied orre-sequenced according to alternative embodiments. It is, therefore, tobe understood that the appended claims are intended to cover all suchmodifications and changes as fall within the true spirit of thedisclosure. Furthermore, in an effort to provide a concise descriptionof the exemplary embodiments, all features of an actual implementationmay not have been described (i.e., those unrelated to the presentlycontemplated best mode, or those unrelated to enablement). It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerous implementationspecific decisions may be made. Such a development effort might becomplex and time consuming, but would nevertheless be a routineundertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure, without undueexperimentation.

The invention claimed is:
 1. A heating, ventilating, and airconditioning (HVAC) system, comprising: a cabinet having a firstsection, a second section, and a barrier configured to direct a firstairflow through the first section and a second airflow through thesecond section; a compressor configured to circulate a working fluidthrough the HVAC system; a first coil disposed in the first section ofthe cabinet and configured to receive the working fluid and to establisha first heat exchange relationship between the working fluid and thefirst airflow directed across the first coil; a second coil disposed inthe second section of the cabinet and configured to receive the workingfluid and to establish a second heat exchange relationship between theworking fluid and the second airflow directed across the second coil;and a fan configured to direct the first airflow across the first coil,the second airflow across the second coil, or both; wherein the firstairflow is not flowing across the first coil when the first coil isinactive and the second airflow is not flowing across the second coilwhen the second coil is inactive.
 2. The HVAC system of claim 1, whereinthe barrier comprises a louver configured to isolate the first airflowacross the first coil from the second airflow across the second coilwhen the first coil is inactive or when the second coil is inactive. 3.The HVAC system of claim 2, wherein the louver is in an open positionwhen the first coil is active and the second coil is active, such thatthe first airflow and the second airflow are not isolated from oneanother.
 4. The HVAC system of claim 1, wherein the fan is a first fan,and further comprising a second fan, wherein the first fan is positionedin the first section and the second fan is positioned in the secondsection.
 5. The HVAC system of claim 4, wherein the first fan is poweredoff when the first coil is inactive, and wherein the second fan ispowered off when the second coil is inactive.
 6. The HVAC system ofclaim 5, wherein the first fan, the second fan, or both comprises aplenum fan.
 7. The HVAC system of claim 5, wherein the first fan, thesecond fan, or both comprises a variable speed fan.
 8. The HVAC systemof claim 1, comprising an additional compressor, wherein the compressoris positioned in the first section and the additional compressor ispositioned in the second section.
 9. The HVAC system of claim 1, whereinthe fan is a first fan configured to direct the first airflow across thefirst coil, and further comprising: a second fan configured to directthe first airflow across the first coil; a third fan configured todirect the second airflow across the second coil; and a fourth fanconfigured to direct the second airflow across the second coil.
 10. TheHVAC system of claim 1, comprising: a third coil configured to receivethe working fluid and to establish a third heat exchange relationshipbetween the working fluid and a third airflow directed across the thirdcoil; a fourth coil configured to receive the working fluid and toestablish a fourth heat exchange relationship between the working fluidand a fourth airflow directed across the fourth coil; and an additionalbarrier configured to isolate the third airflow across the third coil,and the fourth airflow across the fourth coil, wherein the third airflowis not flowing across the third coil when the third coil is inactive,and the fourth airflow is not flowing across the fourth coil when thefourth coil is inactive.
 11. The HVAC system of claim 1, comprising asensor configured to monitor a load demand of the HVAC system, a flowrate of the working fluid through the first coil, a flow rate of workingfluid through the second coil, a voltage supplied to the compressor, ora combination thereof.
 12. The HVAC system of claim 1, comprising acontrol system communicatively coupled to a sensor configured to monitoran operating state of the first coil and the second coil, wherein thecontrol system is configured to adjust the barrier, the fan, or both,such that the first airflow is not flowing across the first coil whenthe first coil is inactive and the second airflow is not flowing acrossthe second coil when the second coil is inactive.
 13. A heating,ventilating, and air conditioning (HVAC) system, comprising: a cabinet;a compressor disposed within the cabinet and configured to circulate aworking fluid through the HVAC system; a first coil disposed within thecabinet and configured to receive the working fluid and to establish afirst heat exchange relationship between the working fluid and a firstairflow directed across the first coil; a second coil disposed withinthe cabinet and configured to receive the working fluid and to establisha second heat exchange relationship between the working fluid and asecond airflow directed across the second coil; a barrier positioned inthe cabinet between the first coil and the second coil, wherein thebarrier is configured to isolate the first airflow across the first coilfrom the second airflow across the second coil; a fan configured todirect the first airflow across the first coil, the second airflowacross the second coil, or both; a sensor configured to determine anoperating state of the first coil and the second coil; and a controlsystem configured to receive feedback from the sensor indicative of anoperating state of the first coil and the second coil, block the firstairflow across the first coil when the feedback indicates that firstcoil is inactive, block the second airflow across the second coil whenthe feedback indicates that the second coil is inactive, direct thefirst airflow across the first coil when the feedback indicates that thefirst coil is active, and direct the second airflow across the secondcoil when the feedback indicates that the second coil is active.
 14. TheHVAC system of claim 13, wherein the sensor comprises a load sensor, aflow sensor, a pressure sensor, or a voltage sensor.
 15. The HVAC systemof claim 13, wherein the barrier comprises a louver configured toisolate the first airflow directed across the first coil from the secondairflow directed across the second coil when the first coil is inactiveor when the second coil is inactive.
 16. The HVAC system of claim 15,wherein control system is configured to adjust the louver from an openposition to a closed position when the first coil or the second coilswitches from an active state to an inactive state.
 17. The HVAC systemof claim 13, wherein the fan is a first fan, and further comprising asecond fan, wherein the barrier forms a first section and a secondsection in the cabinet of the HVAC system, and wherein the first coiland the first fan are positioned in the first section and the secondcoil and the second fan are positioned in the second section.
 18. TheHVAC system of claim 17, wherein the control system is configured tointerrupt a first supply of power to the first fan when the first coilis inactive, and wherein the control system is configured to interrupt asecond supply of power to the second fan when the second coil isinactive.
 19. A method, comprising: receiving feedback indicative of anoperating state of a plurality of coils of a heat exchange unit, whereinthe heat exchange unit includes a cabinet having a plurality of sectionsthat are separated from one another by a barrier, wherein each coil ofthe plurality of coils is disposed within a respective section of theplurality of sections; determining whether a working fluid is flowingthrough a coil of the plurality of coils of the heat exchange unit basedon the feedback; blocking an airflow through the respective section ofthe plurality of sections having the coil of the plurality of coils andacross the coil of the plurality of coils when the feedback indicatesthat the working fluid is not flowing through the coil of the pluralityof coils of the heat exchange unit; and directing the airflow across thecoil of the plurality of coils of the heat exchange unit when thefeedback indicates that the working fluid is flowing through the coil ofthe plurality of coils of the heat exchange unit.
 20. The method ofclaim 19, wherein receiving the feedback indicative of the operatingstate of the coil of the plurality of coils of the heat exchange unitcomprises receiving feedback from a sensor configured to monitor a loadof the heat exchange unit, a flow rate of the working fluid through thecoil of the plurality of coils of the heat exchange unit, a voltagesupplied to a compressor of the heat exchange unit, or a combinationthereof.
 21. The method of claim 19, wherein blocking the airflowthrough the respective section of the plurality of sections having thecoil of the plurality of coils and across the coil of the plurality ofcoils of the heat exchange unit when the feedback indicates that theworking fluid is not flowing through the coil of the plurality of coilsof the heat exchange unit comprises interrupting a supply of power to afan of the heat exchange unit.
 22. The method of claim 19, whereinblocking the airflow across the coil of the plurality of coils of theheat exchange unit when the feedback indicates that the working fluid isnot flowing through the coil of the plurality of coils of the heatexchange unit comprises adjusting a louver from an open position to aclosed position.